Histology of the spleen and liver, and immunohistochemistry of lung and brain tissue from WT, AG-KO, and AG-KO^ALS20αIrecipient animals. (A) Representative spleens from WT, AG-KO, and AG-KO^ALS20αI mouse chimeras stained with hematoxylin and eosin (H&E) and Perls Prussian blue, shown at ×4 original magnification. The spleens of WT animals exhibit sites of high iron staining corresponding to the retention of iron in the macrophages. (B) Representative livers from WT, AG-KO, and AG-KO^ALS20αI recipient animals stained with H&E and Perls Prussian blue, shown at ×10 original magnification. Arrows indicate sites of extramedullary hematopoiesis. (C) Brain tissues from WT, AG-KO, and AG-KO^ALS20αI mouse chimeras were stained using antifibrinogen and anti–von Willebrand factor (VWF) immunohistochemistry. Numbered arrows indicate sites of possible vessel occlusion. (D) Lung tissue from WT, AG-KO, and AG-KO^ALS20αI mouse chimeras was stained using antifibrinogen and anti-VWF immunohistochemistry. Numbered arrows indicate sites of possible vessel occlusion. Arrows 1 and 5 indicate sites of fibrinogen staining, whereas arrows 2-4 and 6 indicate sites of high VWF staining.